Forming die unit for container forming machines



Sept. 10, 1 968 1 D: WMNBERG 3,400,639

FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 7 Sheets-Sheet 1 FIG.

IN VEN TOR wag Sept. 10, 1968 D. WAINBERG 3,400,639

FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 7 Sheets-Sheet 2 Sept. 10, 1968 o. WAINBERG 3,400,639

FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 7 Sheets-Sheet 5 INVENTOR D. WAINBERG Sept. 10, 1968 FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 7 Sheets-Sheet 4 Sept. 10, 1968 o. WAINBERG 3,400,639

FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 7 Sheets-Sheet 5 INVENTOR Sept. 10, 1968 o. WAINBERG 3,400,639

FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 I 7 Sheets-Sheet 6 IN VE/V TOR @M LQ D. WAINVBERG Sept. 10, 1968 v FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Filed Sept. 2, 1965 '7 Sheets-Sheet '7 United States Patent 3,400,639 FORMING DIE UNIT FOR CONTAINER FORMING MACHINES Daniel Wainberg, 4755 Blvd. des Grandes Prairies, St. Leonard, Montreal 38, Quebec, Canada Filed Sept. 2, 1965, Ser. No. 484,569 3 Claims. (CI. 9351) ABSTRACT OF THE DISCLOSURE A device for the locking of'corners when setting up a folding container in a container forming machine, and particularly for folding containers that are provided with locking flaps having bendable locking lips and which articulate from certain of the containers upright walls and with slits located in adjacent upright walls. The forming die has folding edges extending along two opposing sides of the aperture and lug plates with integral projecting lugs extending along and secured to the other sides of the aperture, and hook plates mounted on and secured to the lug plates and having arcuate-shaped guides forming gliding surfaces and which are hook-shaped and the integral hooks of which are directed towards the bottom and extend at an acute angle towards the outside in a direction not facing the plunger corners, the edges of the hooks forming the end of the arcuate-shaped guides of the hook plates.

The invention relates to improvements in a forming die unit for container forming machines as described in the present specification and illustrated in the accompanying drawings that form a part of the same.

The invention consists essentially in the novel features of construction as pointed out broadly and specifically in the claims for novelty following a description containing an explanation in detail of acceptable forms of the invention.

An object of the invention is to devise a forming die that will have little or no moving parts, and consequently will be easier to manufacture, will last longer, have a more positive action during its cooperative engagement by the plunger mechanism in the formation of the carton or container walls and their interlocking, and that will be made of a sturdy and durable construction.

Another object of the invention is to devise a die that may be shaped in the form of a plate-like structure of the required configuration provided with a die aperture or throat, and which may be slidably arranged, suspended or otherwise supported and detachably secured to the [frame of a container forming machine and located beneath the plunger mechanism and in such a way that the aperture or throat will be in alignment with the plunger of the plunger mechanism.

A still further object of the invention is to devise a means for the locking of corners when setting up a folding container in a container forming machine that will require little or no adjustments to any of its fixed parts and rigid blank contact forming parts, with the result that the container forming means are positive in action at all times without deviation in the formation of the containers or cartons from the pre-cut blanks.

A still further object of the invention is in the case where the forming die unit, such as the plunger and the die, may be changed in the container forming machine for assembling sizes, shapes or styles of cartons or containers without in any way interfering with the working parts of the machine.

Still another object of the invention is to devise a forming die unit that will form the walls of the container or carton and interlock the adjacent walls to one another to ice complete the assembly thereof, and without the need or use of the many contrivances, such as movable shelves, movable walls or fingers and other means that are usually included in the construction of other types of container forming dies.

Other objects and novel features of the invention will appear more fully hereinafter from a consideration of the following detailed description when taken in connection with the accompanying drawings illustrative of acceptable forms of the invention. It is expressly understood, however, that the drawings are utilized for the purposes of illustration only and are not to be taken as a definition of the limits of the invention, reference being had for this latter purpose to the appended claims.

In the drawings:

FIGURE 1 is a perspective view of the forming die unit as installed in a container forming machine.

FIGURE 2 is a plan view of an acceptable type of a pre-cut blank adaptable for its formation by the forming die unit.

FIGURE 3 is a perspective view of the container formed from the pre-cut blank (FIGURE 2) after it has been erected through the forming die unit.

FIGURE 4 is a perspective view of the forming die having one of the longitudinal guide rails broken away to disclose the roller unit for facilitating the formation of the container and its exit from the forming die unit.

FIGURE 5 is a perspective detail of the lug plate.

FIGURE 6 is a perspective detail of the hook plate.

FIGURE 7 is an enlarged fragmentary side view illustrating an acceptable method of supporting the roller unit to the lug plate and held under tension.

FIGURE 8 is a cross sectional view as taken along the line 8-8 in FIGURE 4.

FIGURE 9 is an enlarged fragmentary perspective view illustrating a modifications of the combined lug plate and hook plate assembly.

FIGURE 10 is a perspective detail of one of the modified hook plates as illustrated in FIGURE 9.

FIGURE 11 is an enlarged fragmentary perspective view to illustrate the method of interlocking the adjacent walls of the container that is being formed.

FIGURE 12 is an end view illustrating the formation of the container from a pre-cut blank as it is being pushed through the throat of the forming die.

FIGURE 13 is an end view illustrating the formed container as it is leaving the forming die.

FIGURE 14 is a perspective view of a further modified form of the forming 'die unit.

FIGURE 15 is a perspective view of one the lug plates as illustrated in FIGURE 14.

FIGURE 16 is a cross sectional View as taken along the line 16-46 in FIGURE 14.

FIGURE 17 is an enlarged fragmentary perspective view of one end of a modified form of forming die in which a pair of hook plates, provided with individual and integral hooks, are mounted and secured to a lug plate and separated from one another by a separator plate.

FIGURE 18 is a perspective detail of a hook plate and guide member as illustrated in FIGURE 17.

FIGURE 19 is an enlarged perspective detail of the guide member.

Like numerals of reference indicate corresponding parts in the various figures.

In the past, various devices have been used for forming the walls of a pre-cut blank along folded lines and turning inwardly the flaps, flanges or locking lugs projecting from the ends of certain of the container walls so that they will enter apertures or slits located in adjacent container walls and complete corners for the formed containers and lock them together. This has been accomplished by means of a plunger which thrusts a blank into and through the throat or aperture of a forming die.

In many cases, hook-shaped elements or folding members are carried or pivoted in the sides of the plunger for the purpose of opening the apertures or slits in the container walls, engage with the flaps, flanges or locking members and pull them to the inside of the formed container, as well as other devices for pulling the locking members or flaps through openings in the container walls.

Furthermore the forming die has been involved with many contrivances for enlarging and reducing the size and shape of the aperture or throat formed in the forming die, such as the use of movable shelves, and other types of movable walls, fingers, etc., all of which complicates the functional operation of the container forming mechanism, necessitating many adjustments, the repairing and exchanging of these various movable parts and increasing the difficulties of proper maintenance of the container forming machine.

In order that the production of formed containers or cartons from pre-cut blanks be maintained at a high rate, it is imperative that the blank be brought into aligning contact position with the forming die as quickly as possible and placed across the face of the aperture or throat of the forming die so that the plunger, on its downward stroke, will engage the fiat blank and push the same through the aperture or throat of the die and cause the folding of the container or carton walls into upright position with respect to the container or carton bottom wall, and locking together the adjacent upright walls to complete the container corners, all being accomplished, in the present invention, without the need of extraneous movable parts to the forming die unit, and at the same time minimizing the possibility of the pre-cut blank or the partially formed container or carton from being caught in any mechanical portion or part of the forming die or plunger during the forming operation, thereby lessening the danger of breakdowns in the production of the cartons or containers.

Referring to the drawings, the forming die unit comprises a plunger and a forming die 26 that are introduced into a container forming machine 27 and form the means for transforming a pre-cut blank 28 into a formed container or carton 29.

The plunger 25 is suitably shaped to conform with the size and shape of the pre-cut blanks that are to be trans- [formed into containers or carton and has the smooth side walls and the smooth end walls against which the side and end walls of the container are folded. The end walls 31 of the plunger are provided with approximately centrally disposed protuberances 32 which pass through guideways or recesses formed in the forming die, and which will be hereinafter more particularly described.

The plunger 25 has the crosshead 33 which is adjustably, detachably or otherwise secured to the crossbar 34 and is adapted to be brought into alignment with the throat or aperture of the forming die. The ends of the crossbar 34 are secured to the slidable brackets 35 mounted on the vertical posts or rods 36 that are retained within the container (forming machine, and connecting rods 37 are secured to the slidable brackets and to suitable operating means (not shown) that [form a part of the container forming machine for moving the plunger, in downward and upward strokes, in and out of engagement with the throat or aperture of the forming die.

The means for supporting the container forming die may be accomplished in various ways, depending on the type of container forming machine in which the die unit is being used, whether more than one forming die unit will be installed, the number of conveyors used and for other mechanical reasons, but as illustrated in the accompanying drawings, the container forming die 26 is supported on and secured to the cross members 38, which are in turn detachably or otherwise secured to the transverse members 39 of the frame 40 that is secured to and within the container forming machine.

The forming die comprises two identical end members 41 and 42 that are secured to one another by means of the side members 43 and 44. Each of the end members is formed of. a lug plate 45 having the flanges or lateral outer portions 46 and 47 engaging with an secured to the side members 43 and 44, and a pair of lugs 48 and 49 projecting downwardly from the inner face 50 of the lug plate and integral therewith and determinately spaced apart to permit the introduction of the protuberances of the plunger as it passes in and out of the throat or aperture of the forming die. These lugs emanate from the inner face of the lug plate in a predetermined curved arc 51 and then extend downwardly in a vertical direction, and are preferably located adjacent to'the flanges or lateral outer portions 50 of the lug plate.

A hook plate 52 is provided for each of the end members 41 and 42 and has the smooth flat top and bottom surfaces 53 and straight side edges 54 and the straight rear edges 55. The front or inner edges of the hook plate form gliding surfaces which are in the form of a pair of arcuate-shaped guides 56 and 57 which emenate from the side edges 54 in a gradual inward curve 58 and sweep inwardly and outwardly in a deep curvature 59 which terminate into the hooks 60, the latter being integral with the hook plate and project downwardly therefrom. These hooks are predeterminedly spaced from one another and separated by the preferably straight edge portions 61 of the front or inner edges of the hook plate. The hook plates are mounted on and detachably secured to the lug plates and complete the end members.

The end members 41 and 42 are joined together by the parallel supporting members 43 and 44 which engage with the underside of the flanges or lateral outer portions 46 and 47 of the lug plates 45 and are detachably secured therewith. The face plates 63 and 64 have smooth and flat top and bottom surfaces and are secured to the lug plates and abut the sides of the hook plates and are flush with the top surfaces thereof to complete the configuration of the container forming die and the throat or aperture 65 thereof.

The face plates 63 and 64 are detachably secured to the cross members 38 of the frame 40 and are provided with the longitudinal folding edges 66 for effecting the folding of the front and rear walls of the pre-c-ut blank, and cooperate with the hook plates in the assembly and interlocking of the adjacent walls of the carton that is being erected.

The lugs of the lug plates also form the supporting means for a container clearing unit in the guidance and erection of the cartons as they are being erected and completed so that there will be no delay in the removal of the formed containers or cartons and minimize the possibility of any interruption in the production of the erected containers through jamming when leaving the throat of the container forming die, and being of particular assistance when containers of deep depth are being assembled.

The container clearing unit consists of 'a plurality of rollers that are journalled or otherwise secured or supported in the lugs of the lug plate and used for the purpose of engaging with the front and rear walls of the container that is being erected and keeping in close abutment therewith, under spring tension to permit quick frictional engagement and disengagement of the container from the roller under tension.

An acceptable type of container clearing unit, as illustrated in the accompanying drawings, comprises a pair of roller combinations that extend parallel with one another and have their ends supported in the lugs of the lug plates. Each pair of roller combinations consists of a container wall guide roller 68, an intermediate spring flexing roller 69 and a container wall spring-held roller 70, and the ends of these rollers are secured to the lugs of the lug plate.

A flat spring 71 is located at each end of the roller combinations and is secured adjacent to the ends of the guide roller 68, the intermediate roller 69 and the springheld roller 70 by having its upper portion partially encircling the guide roller 68 and then flexed against the intermediate roller. 69 'and continuing on to partially encircle the roller 70 to tension the same against the container as the latter leaves the throat of the container forming die.

Before further particularizing on the constructional features of the forming die unit, it may be mentioned that the forming die unit may be changed in accordance withthe required size, shape or style of container or carton that is to be formed from a pre-cut blank, but the forming die unit, as illustrated in the accompanying drawings, may be used in forming containers such as are fully described in a patent issued to the applicant in the United States under Patent No. 3,191,845 and dated June 29, 1965. I

This type of container, as illustrated in FIGURES 2 and 3, is formed of a blank 28 and has the bottom wall 73, the side walls 74 and 75, the end walls 76 and 77, and the top wall or cover 78. The side walls 74 and 75 have the extension or looking flaps 79' and 80 and which are integral therewith, and are approximately of the same height.

Each of the locking flaps is formed with an offset or protrudingportion 81 in its upper or lateral portion and from which projects downwardly the bendable locking lip or tongue 82 terminating short of the lower transverse edge of the locking lip. This locking lip is creased at 83, where it projects from the offset or protruding portion, so that it may be folded inwardly to abut the inner'face of the offset or protruding portion, and this forms one part of the interlocking means.

The end walls 76 and 77 have the transverse bendable flaps or flanges 84 extending along their top portions and have the vertical slits 85 and 86 made in their upper portions and suitably spaced from their outer vertical edges and terminating considerably short from their joinder crease lines .with the bottom wall. These slits 85 and 86 extend upwardly into the transverse flaps 84 at an offset angle to form the continuation of the approximate vertical slits into angular slits 87 in order to receive the cham'fered edges 88 of the locking fi'aps 79 and 80. This arrangement of the slits'forms the other part of the interlocking means.

It will be noted that .the height of the protuding portions and the locking lips, in their extended positions, of the locking flaps are longer than the height of the vertical slits. formed in the end walls, so that it is necessary to fold back the locking flaps against the faces of the protruding portions in order that the combined protruding portions and their locking lips may be inserted through the slits.

When the upright walls are to be joined and locked together, the locking flaps are folded at right angles to the vertical folds of the uprights from the bottom wall, and the locking lips, projecting downwardly from the lower extremities of the protruding portions of the locking flaps, are folded vertically so as to abut the inner surfaces of the protruding portions. The end walls are folded upwardly in a vertical direction from the bottom wall and with their articulated bendable transverse flaps or flanges arranged in vertical alignment, are flexed so that the slits will be in position for receiving the protruding portions and locking lips of the locking fiaps, thus completing the locked corners 89 for the container in its set-up position.

The folded-locking fiaps are-simply directed into and through thecommon slits of the transverse flaps and the end walls by bringing the walls into an upright position, with the folded lock-ing flaps articulating inwardly in upright angular positions from the upright side walls, thus allowing the protruding portions and the folded locking lips to penetrate through the slits and engage with the inner faces of the end walls. The locking lips are automatically released from their folded abutment with the protruding portions and unfold themselves of their own volition and pliancy, and as these locking lips extend below the lower extremities of the slits, the offset or protruding portions of the locking flaps are in contiguous back-to-back engagement with the inner faces of the end walls. It will be noted that there is positive interlocking of the side and end walls together and allowing for little or no lateral or vertical movement possible, and consequently preventing any displacement of the locking units from their locked positions.

In certain instances, where the size, style and shape of the pre-cut blank is such that it is necessary for the hook plate and its accompanying hooks to be adjusted either c01- lectively or individually, it may be desirable to have a multiple hook plate rather than a single hook plate.

In FIGURES 9 and 10 of the drawings there is illustrated a modified form of the combined lug plate and hook plate assembly in which separate hook plates are used with individual hooks and are adjustably mounted on the lug plate. These hook plates 90 and 91 and their separator plate 92, when assembled, are practically similar in configuration to the hook plate as illustrated in FIG- URE 6, with the exception that they are individually adjustable on the lug plate to which they are detachably secured.

Each of the hook plates 90 and 91 is similarly constructed and consists of smooth fiat top and bottom surfaces 94, straight side edges 95 and a straight rear edge 96. The front or inner edge of the hook plate is in the formation of an arcuate-shaped guide 97 which emanates from one of the side edges 95 in a gradual inward curve 96 and sweeps inwardly and outwardly in a deep curvature 98 which terminates into a hook 99 that is integral With the hook plate and projects downwardly therefrom and merges with the other side edge of the hook plate and is flush therewith to form a corner 100.

The separator plate 92 also has smooth fiat top and bottom surfaces with straight side edges and front and rear edges and is placed approximately centrally on the top face of the lug plate 93 and secured thereto. The separator plate is abutted on either side by the hook plates 90 and 91 and is flush with their top surfaces. The hook plates are pivotally secured to the top face of the lug plate and are provided with arcuate slots 101 through which fastening members 102 extend to lock the hook plates on the lug plate in accordance to their required adjusted positions.

Another important purpose in the use of this modified form of hook plate is to enable the forming of containers from pre-cut blanks that are provided with a single locking flap at each end, and in such cases, each of the end members of the container forming die will consist of a hook plate having a single hook mounted on and secured to a lug plate having a single lug.

Although it has been stated throughout the description and shown in the accompanying illustrations that the hooks of the hook plates are so located as to engage with the end walls of the container that is being formed, it wil be understood that the hooks may be so placed as to engage with the corners or sides of the container that is being erected, according to the size, style and shape of the pre-cut blanks, without in any way departing from the general structure of the container forming die unit.

In FIGURES 14, 15 and 16 the general structure of the container forming die is shown as being applied to an adjustable type of forming die for receiving pre-cut blanks of varying lengths without the necessity of replacing the forming die with another die.

In this modification the end members 103 and 104 are identical in shape with the end members 41 and 42, as illustrated in FIGURE 4, with the exception that the roller combinations 105 of the container clearing unit do not extend along the length of the forming die or join the end members to one another, but only project away from the lugs of the lug plates for a predetermined distance to engage portions of the side walls of the con tainer that are in the approximate areas of the container corners.

Each of the end members has a cross member 106 secured to its underside and which projects beyond the side edges thereof to engage in the channel members 107 and 108; the cross members, with their attached end members, are moveable along the channel members to predetermined locations and locked therewith to complete the throat of the die.

The channel members are flush with the top surfaces of the hook plates and form longitudinal folding edges 109 of the forming die. The channel members are detachably secured in any suitable manner to the die supporting frame of the container forming machine.

In certain instances, it has been found that, in the formation stage of converting the pre-cut blank into a container, the locking lips with their accompanying flaps do not bend at the right moment for engagement with the walls of the container are not secured together and the formation of the container is incomplete, the blank is often mutilated, and the production of the container assembly is slowed down.

Such unexpected breakdowns may be caused for various hooks of the hook plates, and consequently the adjacent reasons, such as in the event that the crease lines that divide the locking lips from the protruding portions of the locking flaps of the precut blanks are inadvertently omitted, and, in consequence, the locking lips are not likely to bend when they are brought into engagement with the hooks of the hook plates.

In order to overcome such defects and assure the proper bending of the locking lips, guide members 110 may be attached to the forming die and located thereon in such a way that they will engage the locking lips of the locking flaps, if the lips are not folded at the proper moment, and cause the locking lips to bend so as to permit their ingress into the slots formed in the adjacent walls of the container.

An acceptable type of guide member 110 is illustrated in FIGURES 17, 18 and 19 of the drawings, and consists of a fiat plate 111 having a guide bar mounting 112 at one end provided with a threaded aperture, which is adapted to be engaged by the guide bar 113 having the threaded portion 114 and which is adjustably secured to the guide bar mounting. The guide member is provided with a slot 115 through which it is adjustably secured to the hook plate 116.

Each of the hook plates has a guide member detachably and adjustably secured thereto in such a way that the guide bar will extend over the curvature formed along one edge of the hook plate and over the top of the lug plate 118 to the edge of the lug 119, projecting downwardly from the lug plate, and adjacent to the hook 117 of the hook plate 116.

It will of course be understood that the guide members may be modified and are adapted to be used in the various forms of the forming die and may be omitted therefrom, if desirable.

In erecting a container from a pre-cut blank, the precut blank is deposited, in a flat state, over the throat formed in the forming die and is accurately aligned with respect to the bottom end surface of the plunger. When the plunger descends towards the forming die and makes contact with the bottom wall of the blank, it will force the blank through the throat of the die, thereby folding the container walls into upright positions with respect to the bottom wall of the container.

As the walls of the blank are being folded in an upright position, the locking flaps, with their protruding portions and locking lips, are bent in a lateral direction and guided in proper position by the arcuate-shaped guides formed in the hook plates and are brought in contact with the hooks of the hook plates which cause the locking lips of the protruding portions of the locking flaps to be bent in a back-to-back formation with the inner faces of the protruding portions of the locking flaps, in order that they may enter into and through the slits formed in the end walls. Simultaneously, the hooks deflect the end walls and expand the space formed by the slits of the end walls to permit the easy introduction of the protruding portions and their abutting locking lips into and through the slits of the end walls.

The deflection of the end walls is further augmented by means for exerting pressure in opposite directions to the end walls for opening and expanding the slits formed therein as the container walls are being erected, so that the locking lips of the locking flaps, in their bent position, which is effected by the hooks of the hook plate, may be directed into and through the opened slits of the end walls.

This is accomplished by utilizing the protuberances, which project from the end walls of the plunger, to exert outward pressure against the central portions of the container end walls that are located between the vertical slits in each of these container end walls, While simultaneously, pressure is exerted inwardly to the portions of the end walls that extend from their vertical slits to their vertical edges, by means of the lugs which project downwardly and outwardly from their integral lug plates, thus expanding the slits for the easy insertion of the folded locking lips. In this way the possibility of the non-opening of the slits in the end walls, at the proper time, is reduced to a minimum.

The plunger having now about completed its downward stroke through the throat of the forming die, all the walls of the container have now been folded upwardly, the locking flaps are now at right angles to the side walls and abut the end walls; and the protuberances with their folded locking lips have been inserted through the slits of the end walls.

The plunger then completes its downward stroke to eject the formed container from the throat of the forming die and the locking lips are free to expand on the inside of the container walls and complete the locking of the corners of the container.

Since certain changes may be made in the above invention and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What I claim is:

' 1. A forming die unit for the locking of corners when setting up a folding container in a container forming machine, the container being made from a one-piece pre-cut blank having a bottom wall and articulating upright walls, certain of the upright walls having articulating locking flaps with integral bendable locking lips and certain of the upright walls having slits, said forming die comprising a forming die having an aperture therethrough and a plunger situated in alinement with the aperture of the forming die, said forming die having folding edges extending along two opposing sides of the aperture, immovable lug plates extending along the other opposing sides of the aperture and having integral propjecting lugs extending downwardly and outwardly into the aperture, said forming die characterized by the fact that hook plates are superimposed on said lug plates and have arcuate-shaped guides forming gliding surfaces and which are hook-shaped and the integral hooks of which are directed towards the bottom and extend at an acute angle towards the outside into a direction not facing the plunger corners, and the edges of the hooks form the end of the arcuate-shaped guides of said hook plates, said arcuate-shaped guides extending, starting from the plunger corners concavely towards the hooks as guides for the locking flaps of the container which are provided with bendable locking lips.

2. A forming die unit for the locking of corners when setting up a folding container in a container forming machine as claimed in claim 1, characterized by the fact that the forming die, having an aperture therethrough, has two of the opposing sides of the aperture formed of face plates, providing folding edges, and having smooth and flat top and bottom-surfaces and which are secured to lug plates that are attached to the other opposing sides of the aperture and abut the hook plates that are mounted on and secured to the lug plates.

3. A forming die unit for the locking of corners when setting up a folding container in a container forming machine, the container being made from a one-piece pre-cut blank having a bottom wall and articulating upright w-alls, certain of the upright walls having articulating locking flaps with integral bendable locking lips and certain of the upright walls having slits, said forming die unit comprising a forming die having an aperture therethrough and a plunger situated in alinement with the aperture of the forming die, said forming die having folding edges extending along two opposing sides of the aperture in said forming die, said forming die unit characterized by the fact that a lug plate extends along each of the other opposing sides of the aperture and is mounted and secured to said forming die, each of said lug plates having a pair of integral lugs spaced apart from one another and which project from the lug plate in an outward and downward direction into the aperture of said forming die, a pair of hook plates spaced apart from one another and mounted and secured to each of said lug plates, each hook plate having an arrcuate-shaped guide forming a gliding surface and which is hook-shaped and the integral hook of which is directed towards the bottom and extends at an acute angle towards the outside into a direction not facing a plunger corner, and the edge of the hook forming the end of the arcuate-shaped guide of said hook plate, said arcuate-shaped guide extending, starting from a plunger corner concavely towards the hook as a guide for a locking flap of the container which is provided with a bendable locking lip, and a separator plate secured to said lug plate and inserted between each pair of hook plates and abutting the adjacent sides thereof and having a top surface flush with the top surfaces of said hook plates.

References Cited UNITED STATES PATENTS 393,404 11/1888 Stout 9359 858,172 6/1907 Godfrey 93-59 X 2,516,624 7/1950 Guyer 9351 2,604,827 7/1952 Hickin. 2,860,549 11/1958 Mancuso. 2,930,294 3/ 1960 Ritscher.

3,067,654 12/1962 Nichols.

3,115,073 12/1963 Kreimendahl 9351 3,168,018 2/1965 Dunn 9351 3,191,845 6/ 1965 Wainberg 229-32 FOREIGN PATENTS 870,624 6/1961 Great Britain.

WAYNE A. MORSE, JR., Primary Examiner. 

